1. Field of the Invention
This invention relates to drilling assemblies of the type used to drill holes in a subterranean formation, and more particularly to drilling assemblies utilizing the cutting action of a plurality of small high pressure fluid streams directed against the face of a formation being drilled. Drills of this general type are frequently used to drill through coal formations to provide openings in the formation through which methane gas can be vented or removed by vacuum.
2. Description of the Prior Art
As noted above, drilling assemblies of the general type to which this invention relates are known. One such assembly is described in my copending application Ser. No. 667,785 filed Mar. 17, 1976. The device described in that application is in many respects similar to the device of the present invention, which is best described as an improvement thereover.